Kanto: Lt. Surge (Electric types are among my favorite types and the rest are not in the rosters of Gym leaders in this region)
Johto: Jasmine (gotta love the Steel type)
Hoenn: Norman (because it is the only solid trace of your father in a Pokemon game)
Sinnoh: Volkner (highest ranked Electric user in any Pokemon game and currently my sprite for Pokemon Online)
Unova: Caitlin (it is nice that to have someone from the 4th Gen Battle Frontier)